Water Quality Indices

If pH is less than 2. Convert pH to water quality index. If turbidity is greater than ntu, the quality index equals 5. Convert turbidity to water quality index. If biochemical oxygen demand is greater than 30 ppm, the quality index equals 2. Convert biochemical oxygen demand ppm to water quality index. If nitrate nitrogen is greater than ppm, the quality index equals 1.

Convert nitrates ppm to water quality index. About one-third of this area is fragile mangrove forest, the second largest mangrove forest in the world. The biodiversity of the Niger Delta is very high with the area containing diverse plant and animal species, including many endangered, exotic and endemic animals and plants[11].

The Niger Delta has an estimated population of over 30 million people[12], the bulk of which lives in rural fishing and farming communities. Regrettably, activities of multinational oil companies have recently been linked to degradation of the natural environment, pollution and low agricultural productivity[14, 15] as well as insecurity of lives and property, hence, a reduction in quality of life expectations in Niger Delta communities[13]. The Niger Delta region is therefore of immense geopolitical, ecologic and economic importance.

It is also an important agro-climatic region in Nigeria. Map of the Niger Delta region of Nigeria 2. Sample Collection Pipe borne water, borehole water and stream water samples from different states in the Niger Delta region of Nigeria were collected. All plastics and glasses utilized were pre-treated by washing with dilute HCl 0. They were then air-dried in a dust free environment. At the collection point, containers were rinsed with relevant samples twice and filled with samples and then corked tightly. Physico-Chemical Analysis The analysis of various physico-chemical parameters analyzed namely pH, total alkalinity, chlorides, sulphate, nitrate, total hardness, calcium, magnesium, electrical conductivity, dissolved oxygen, biochemical oxygen demand, total dissolved solids and total suspended solids were carried out as per methods described in[17,18].

Calculation of Water Quality Index In this study, for the calculation water quality index, thirteen important parameters were chosen. The weighted Arithmetic index method[19] has been used for the calculation of WQI in this study. Further, quality rating or sub index was calculated using the following expression. The overall WQI is calculated by the following equation. Results and Discussion The results of the physico-chemical parameters of the different samples of pipe borne water, bore hole water and stream water analysed are as shown in Tables 3, 4 and 5 respectively.

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Water quality index indicates the quality of water in terms of index number which represents overall quality of water for any intended use[10]. In this study, the WQI is established from important physico-chemical parameters such as pH, total alkalinity, chlorides, sulphate, nitrate, total hardness, calcium, magnesium, electrical conductivity, dissolved oxygen, biochemical oxygen demand, total dissolved solids and total suspended solids. The results indicate that the different water samples analysed from pipe born and borehole water are safe for safe for human consumption and for other domestic purposes while the samples analysed from stream water are not safe for human consumption[8].

The above water quality index is supported by the following physico-chemical parameters, namely pH, total alkalinity, chlorides, sulphate, nitrate, total hardness, calcium, magnesium, electrical conductivity, dissolved oxygen, biochemical oxygen demand, total dissolved solids and total suspended solids. The variations of the above physico-chemical parameters observed among the different water samples were all within the recommended standards. Among all the physico-chemical parameters selected for the WQI calculations, pH is an important parameter which determines the suitability of water for various purposes [20].

In the present study, pH ranges from 6. This shows that the pH rabge obtained for the stream waqter samples 5. High pH levels are undesirable since they may impart a bitter taste to the water. Furthermore, the high degree of mineralization associated with alkaline water will result in the encrustation of water pipes and water-using appliances.

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The combination of high alkalinity and calcium with low pH levels may be less corrosive than water with a combination of high pH, low alkalinity and calcium content. High pH levels also depress the effectiveness of disinfection by chlorination, thereby requiring the use of additional chlorine or longer contact times[5]. The pH of most natural water bodies range from 6. In natural water, dissolved solids are composed mainly of carbonates, bicarbonates, chlorides, sulphates, phosphates, nitrates, calcium, magnesium, sodium, potassium, iron and manganese[5].

They originate from dissolution or weathering of the rocks and soil, including dissolution of lime, gypsum and other slowly dissolved soil minerals. Total dissolved solids TDS in all the water samples analysed were within the recommended standards for drinking water. TDS in drinking water has also been associated with natural source, sewage, industrial wastewater, urban run-off and chemical used in water treatment process[24].

Hardness is a measure of the ability of water to cause precipitation of insoluble calcium and magnesium salts of higher fatty acids from soap solutions.

Water Quality Index Calculator

The total hardness values of the present study were found to range between Drinking water standards, recommending Agencies and unit weights. Magnesium is essential for chlorophyll growth and acts as a limiting factor for the growth of phytoplankton.



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The quantities of Calcium in natural water depend upon the type of rocks. Small concentration of calcium is beneficial in reducing the corrosion in water pipes. Magnesium hardness particularly associated with sulphate ion has laxative effect on persons unaccustomed to it. In the present study, Calcium and Magnesium contents are with within the recommended standards. Dissolved oxygen analysis measures the amount of gaseous oxygen O 2 dissolved in an aqueous solution.

Dissolved Oxygen DO is an important parameter which is essential to the metabolism of all aquatic organisms that posses aerobic respiration[25]. Presence of DO in water may be due to direct diffusion from air and photosynthetic activity of autotrophs[26]. Oxygen can be rapidly removed from the waters by discharge of oxygen demanding wastes[20].

Water Quality Assessment in Terms of Water Quality Index

The values of DO obtained in this study are within the recommended standards except for some samples of stream water analysed. The biochemical oxygen demand, abbreviated as BOD, is a test for measuring the amount of biodegradable organic material present in a sample of water.



A usual water quality index method was developed by paying great rigor in selecting parameters, developing a common scale and assigning weights. The proposed method for comparing the water quality of various water sources is based upon nine water quality parameters such as temperature, pH, turbidity, fecal coliform, dissolved oxygen, biochemical oxygen demand, total phosphates, nitrates and total solids [ Water Sewage Works , The water quality data are recorded and transferred to a weighting curve chart, where a numerical value of Qi is obtained. Larger image png format Tables index Veiw figure View current table in a new window.

CCME WQI provides a consistent method, which was formulated by Canadian jurisdictions to convey the water quality information for both management and the public. Moreover, a committee established under the Canadian Council of Ministers of the Environment CCME has developed WQI, which can be applied by many water agencies in various countries with slight modification [ 37 , 38 , Environ.

A Water Quality Index for Ecology's Stream Monitoring Program

This method has been developed to evaluate surface water for protection of aquatic life in accordance to specific guidelines. The parameters related with various measurements may vary from one station to the other and sampling protocol requires atleast four parameters, sampled atleast four times [ Wat.

Therefore, five categories have been suggested to categorize the water qualities which are summarized in Table 1. The parameters covered in this method are temperature, dissolved oxygen DO , biochemical oxygen demand BOD , pH, ammonia and nitrate nitrogen, total phosphorus, total solids and fecal coliform [ J. It expresses water quality status and trends for the legislatively mandated water quality status assessment. The index is free from the arbitration in weighting the parameters and employs the concept of harmonic averaging. The mathematical expression of this WQI method is given by. Furthermore, the rating scale of this OWQI has also been categorized in various classes, which are given under Table 1 [ 43 ].

Weighted arithmetic water quality index method classified the water quality according to the degree of purity by using the most commonly measured water quality variables. The method has been widely used by the various scientists [ Report Opinion, 2 9.

Publication Summary

The unit weight Wi for each water quality parameter is calculated by using the following formula:. A comparison of all these water quality indices is also performed under the study considering their merits and demerits. Table 3 explains about the merits and demerits of WQI methods. After the study of different water quality indices, it may be inferred that the aim of WQI is to give a single value to water quality of a source alongwith reducing higher number of parameters into a simple expression resulting into easy interpretation of water quality monitoring data.

Moreover, this is an effort to review the important indices used in water quality vulnerability assessment and also provides information about indices composition and mathematical forms.

Science and Education Publishing

These indices utilize various physico-chemical and biological parameters and have been resulted as an outcome of efforts and research and development carried out by different government agencies and experts in this area globally. In spite of all the efforts and different discussed indices being used globally, no index has so far been universally accepted and search for more useful and universal water quality index is still going on, so that water agencies, users and water managers in different countries may use and adopted it with little modifications. The authors are thankful to USERC administration to provide necessary infrastructure to complete this work.

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